(1) Field of the Invention
This invention relates to a metal-containing curable resin composition which is widely employed as adhesives, casting resins, paints and the like. More particularly, it relates to a metal-containing self-curing epoxy resin composition which comprises a metal-containing compound represented by the general formula; EQU HO--R.sub.1 --OOC--R--COOMOOC--R--COO--R.sub.1 --OH [1]
(wherein, R.sub.1 is the residue of a glycol, R is a residue of dibasic acid anhydride and M is a divalent metal), a dibasic acid anhydride and an epoxy resin.
(2) Description of the Prior Art
Epoxy resins have been widely employed as adhesives, casting resins, paints and the like, but addition of curing agents is required to effect curing of conventional epoxy resins. The addition of such curing agent to epoxy resins is troublesome, in that (a) the amount of curing agent to be added must be determined by measuring epoxy equivalent of the epoxy resin to be cured, (b) some curing agents are toxic. On the other hand, according to the present invention, a metal-containing compound represented by the general formula [1] described above participates in curing reaction as a component of the present composition to form a cured product as well as catalyzes the curing reaction without addition of the above-mentioned curing agent.
Heretofore, a method of introducing ionic bonds into polymer chains has been widely carried out in the art. The method comprises preparing a polymer containing carboxyl groups at the ends or sides of the polymer chain according to a conventional process and then neutralizing the carboxyl groups contained in the polymer with a metallic ion-forming agent. This method, however, has difficulty in that the neutralization reaction does not sufficiently proceed and the unreacted metallic ion-forming agent must be removed. Presence of the unreacted metallic ion-forming agent may result in opaqueness of the resulting polymer. Further, the neutralization reaction produces by-products such as water. Furthermore, according to the method, it is very difficult to introduce ionic bonds effectively into a three-dimensional polymer.
An object of the invention is to provide a novel curable resin composition which can be appropriately employed as adhesives, casting resins, paints and the like.
Other objects of the invention will be made clear in the following description.
Incidentally, the term "metal-containing" used herein means that the metal is contained via metal-ionic bond (ionic bond of metal) in the compound represented by the general formula [1] which is a main component of the present curable composition as well as in the resulting cured resin product.